Instructions:

1. Melt the Chocolate:
   In a heatproof bowl set over a pot of simmering water (double boiler), melt the chopped chocolate, butter, and coffee (or milk), stirring until smooth. Remove from heat and stir in vanilla extract and salt. Let cool slightly.
2. Prepare the Egg Mixture:
   In a separate heatproof bowl, whisk the egg yolks and sugar until well combined. Place the bowl over the simmering water and whisk constantly for about 2 minutes until the mixture thickens slightly. Remove from heat and slowly whisk into the melted chocolate mixture. Let cool to room temperature.
3. Whip the Cream:
   In a chilled mixing bowl, beat the heavy whipping cream until soft peaks form. Gently fold half of the whipped cream into the chocolate mixture to lighten it, then fold in the remaining whipped cream until fully combined and smooth.
4. Assemble the Cups:
   Spoon or pipe the chocolate mousse into serving cups or ramekins. Cover and refrigerate for at least 2 hours (or overnight) to allow the mousse to set.
5. Garnish and Serve:
   Before serving, top each mousse cup with fresh strawberry slices, a dollop of whipped cream, and a sprinkle of chocolate shavings or cocoa powder for extra elegance.